Optical device and LiDAR system including the same

Abstract

An optical device according to an embodiment may include: a plurality of light sources configured to emit laser beams; a light direction changing unit comprising at least one of a prism and a mirror, provided on traveling paths of the laser beams, and configured to focus the laser beams at one point by changing travelling directions of the laser beams to form constant angles between the traveling paths of the laser beams; and a scanning mirror configured to perform two-dimensional scanning by reflecting the laser beams received from the light direction changing unit.

What is claimed is: 
     
       1. An optical device comprising:
 a plurality of light sources separated from each other in a vertical direction, and configured to emit laser beams in parallel in a horizontal direction; 
 a light direction changing unit comprising a plurality of prisms or a plurality of mirrors provided on traveling paths of the laser beams, which travel in parallel from the plurality of light sources to the plurality of prisms or the plurality of mirrors, and configured to focus the laser beams at one point by changing travelling directions of the laser beams to form non-zero angles between the traveling paths of the laser beams at the one point; and 
 a scanning mirror configured to perform two-dimensional scanning by reflecting the laser beams received from the light direction changing unit. 
 
     
     
       2. The optical device of  claim 1 , wherein the light direction changing unit is further configured to focus the laser beams on the one point located at the scanning mirror. 
     
     
       3. The optical device of  claim 1 , further comprising:
 a plurality of first collimators provided one by one on the traveling paths of the laser beams between the plurality of light sources and the light direction changing unit to reduce a first spread angle in a first axial direction of the laser beams; and 
 a plurality of second collimators provided one by one on the traveling paths of the laser beams between the plurality of first collimators and the light direction changing unit to reduce a second spread angle in a second axial direction of the laser beams, wherein the second axial direction is different from the first axial direction. 
 
     
     
       4. The optical device of  claim 3 , wherein the plurality of light sources are arranged at equal intervals in the vertical direction. 
     
     
       5. The optical device of  claim 1 , wherein the scanning mirror comprises a rotation mirror configured to rotate in both directions about a first axis and a second axis perpendicular to the first axis. 
     
     
       6. The optical device of  claim 5 , wherein a first angle range of rotation of the rotation mirror with respect to the first axis is in a range from 0 degrees to M*β degrees, and a second angle range of rotation of the rotation mirror with respect to the second axis is in a range from −90 degrees to +90 degrees, and
 wherein M denotes a natural number, and β denotes an angle. 
 
     
     
       7. The optical device of  claim 6 , wherein a number of the plurality of light sources is N, and a number of vertical channels of a scan area by the optical device is N*M, and
 wherein N denotes a natural number. 
 
     
     
       8. The optical device of  claim 4 , wherein the light direction changing unit comprises the plurality of prisms. 
     
     
       9. The optical device of  claim 8 , wherein two prisms, from among the plurality of prisms, provided at positions symmetrical with respect to a center of the light direction changing unit have an exit surface of a same inclination angle. 
     
     
       10. The optical device of  claim 8 , wherein a first inclination angle of a first exit surface of a prism, from among the plurality of prisms, disposed relatively far from a center of the light direction changing unit is greater than a second inclination angle of a second exit surface of the prism disposed relatively close to the center of the light direction changing unit. 
     
     
       11. The optical device of  claim 8 , wherein a first distance between a first prism, from among the plurality of prisms, disposed at a relatively outer side with respect to a center of the light direction changing unit and the second collimator adjacent thereto is greater than a second distance between a second prism, from among the plurality of prisms, disposed at a relatively inner side with respect to the center of the light direction changing unit and the second collimator adjacent thereto. 
     
     
       12. The optical device of  claim 8 , wherein the plurality of prisms are arranged so that an inclination angle of an exit surface of each prism is sequentially increased in the vertical direction. 
     
     
       13. The optical device of  claim 8 , wherein the plurality of prisms are arranged so that distances between each prism and the point where the laser beams are focused are equal. 
     
     
       14. The optical device of  claim 1 , wherein the light direction changing unit comprises the plurality of mirrors. 
     
     
       15. The optical device of  claim 3 , wherein the plurality of first collimators and the plurality of second collimators comprise cylindrical lenses. 
     
     
       16. The optical device of  claim 15 , wherein the plurality of first collimators are integrally formed. 
     
     
       17. The optical device of  claim 15 , wherein a first collimator of the plurality of first collimators and a second collimator of the plurality of second collimators adjacent to the first collimator in the travelling directions of the laser beams are integrally formed. 
     
     
       18. The optical device of  claim 3 , further comprising:
 a first aperture provided between the plurality of light sources and the plurality of first collimators to suppress divergence of the laser beams; and 
 a second aperture provided between the plurality of second collimators and the light direction changing unit to suppress the divergence of the laser beams. 
 
     
     
       19. The optical device of  claim 1 , wherein the scanning mirror comprises a polygon mirror having M reflection surfaces of different inclination angles,
 wherein M denotes a natural number. 
 
     
     
       20. The optical device of  claim 19 , further comprising a plurality of second light sources and a second light direction changing unit that are disposed at positions symmetrical with the plurality of light sources and the light direction changing unit with the polygon mirror,
 wherein the polygon mirror is disposed at a center between the positions of the plurality of second light sources and the second light direction changing unit and positions of the plurality of light sources and the light direction changing unit. 
 
     
     
       21. The optical device of  claim 20 , further comprising:
 a first reflection mirror configured to reflect a first laser beam of the laser beams received from the light direction changing unit so that the first laser beam is incident on a first reflection surface of the polygon mirror; and 
 a second reflection mirror that reflects a second laser beam of the laser beams received from the second light direction changing unit so that the second laser beam is incident on a second reflection surface that is different from the first reflection surface of the polygon mirror. 
 
     
     
       22. The optical device of  claim 21 , wherein the first reflection mirror and the second reflection mirror are arranged to be misaligned from each other so that a number of vertical channels of the optical device is increased. 
     
     
       23. The optical device of  claim 21 , wherein the first reflection mirror and the second reflection mirror are arranged with angles to increase a total horizontal viewing angle by separating a first horizontal viewing angle by the first laser beam reflected by the first reflection mirror from a second horizontal viewing angle of the second laser beam reflected by the second reflection mirror. 
     
     
       24. The optical device of  claim 1 , further comprising:
 a controller configured to generate driving signals for driving the plurality of light sources. 
 
     
     
       25. The optical device of  claim 24 , wherein the controller is further configured to selectively transmit the driving signals to at least two light sources separated from each other by at least one light source disposed between the at least two light sources, among the plurality of light sources. 
     
     
       26. A light detection and ranging (LiDAR) system comprising:
 an optical device of configured to emit laser beams towards an object; and 
 a detector configured to receive the laser beams reflected from the object, 
 wherein the optical device comprises: 
 a plurality of light sources separated from each other in a vertical direction, and configured to emit the laser beams in parallel in a horizontal direction; 
 a light direction changing unit comprising a plurality of prisms or a plurality of mirrors provided on traveling paths of the laser beams, which travel in parallel from the plurality of light sources to the plurality of prisms or the plurality of mirrors, and configured to focus the laser beams at one point by changing travelling directions of the laser beams to form non-zero angles between the traveling paths of the laser beams at the one point; and 
 a scanning mirror configured to perform two-dimensional scanning by reflecting the laser beams received from the light direction changing unit. 
 
     
     
       27. The LiDAR system of  claim 26 , wherein the detector is provided at a position where the laser beams reflected from the object are directly received. 
     
     
       28. The LiDAR system of  claim 26 , wherein the detector is provided at a position where the laser beams reflected from the object are received after the laser beams reflected from the object are re-incident on a reflection surface of the scanning mirror, and
 the reflection surface of the scanning mirror is configured to reflect the laser beams emitted from the plurality of light sources to the object.